Towards a terramechanics for bio-inspired locomotion in granular environments

TL;DR

This paper develops a new terramechanics framework for bio-inspired locomotion in granular media, combining experiments, simulations, and theory to better understand and predict locomotor interactions with such complex environments.

Contribution

It introduces a resistive force theory for granular media and applies it to analyze bio-inspired robot locomotion, advancing the understanding of interactions in granular environments.

Findings

Resistive force theory effectively models complex intrusions in granular media.

Experimental and DEM data reveal key interaction mechanics during locomotion.

Bio-inspired robots demonstrate varied performance based on granular media properties.

Abstract

Granular media (GM) present locomotor challenges for terrestrial and extraterrestrial devices because they can flow and solidify in response to localized intrusion of wheels, limbs, and bodies. While the development of airplanes and submarines is aided by understanding of hydrodynamics, fundamental theory does not yet exist to describe the complex interactions of locomotors with GM. In this paper, we use experimental, computational, and theoretical approaches to develop a terramechanics for bio-inspired locomotion in granular environments. We use a fluidized bed to prepare GM with a desired global packing fraction, and use empirical force measurements and the Discrete Element Method (DEM) to elucidate interaction mechanics during locomotion-relevant intrusions in GM such as vertical penetration and horizontal drag. We develop a resistive force theory (RFT) to account for more complex intrusions. We use these force models to understand the locomotor performance of two bio-inspired robots moving on and within GM.